VANCOUVER — A retired doctor who spent years treating drug addiction says he has seen the healing powers of a psychedelic plant that a Vancouver Island man was studying in Peru before he was killed by a mob that blamed him for a shaman’s death.

Dr. Gabor Mate said ayahuasca grows in the jungle and is brewed with other plants into a thick concoction people drink at ceremonies in countries such as Peru, Costa Rica and Brazil.

The drug is illegal in Canada. Health Canada said in a statement that ayahuasca is a controlled substance that is considered to have no medical benefit.

Mate said the hallucinogenic medicine is used as part of ancient aboriginal practices to help people tap into childhood trauma with support from a leader, and he has seen its power at work in Peru, and Costa Rica, from where he returned two weeks ago after facilitating ceremonies involving the plant.

“I’ve known people whose addiction has stopped,” he said, adding he has worked with ayahuasca for 10 years. “I know people who’ve recovered from medical diseases that otherwise they got little help for. I know a woman who tried to kill herself 17 times, who is no longer suicidal.

“It’s not like a drug you give to somebody. It’s more that it opens up portals into yourself, understanding self in a new way and having a deeper vision of reality. It’s that understanding of the self and a clearer view of reality that helps you heal.”

Peru’s attorney general has ordered the arrest of two suspects in the killing of 41-year-old Sebastian Woodroffe, who had travelled to the Amazon rain forest to study hallucinogenic medicine. Officials said forensic experts were studying Woodroffe’s body to determine whether he had any involvement in the death of Olivia Arevalo, an octogenarian plant healer from the Shipibo-Konibo tribe in northeastern Peru.

A Canadian Institute for Substance Use Research study published in 2013 in Canadian Drug Abuse Reviews says ayahuasca-assisted therapy delivered in 2011 in a B.C. rural First Nations community experiencing substance use appeared to show improvements in outlook, hopefulness and empowerment and that more research was warranted.

Mark Haden, adjunct professor at the University of British Columbia’s school of population and public health, said the plant helps people gain insight and works toward healing but problems occur in impoverished communities where shamans aren’t accountable.

“I think psychedelic drugs should be legalized in Canada and North America within a context that allows for people to experience psychedelic medicines in a supervised setting and the supervisors need to be part of an accountable professional body,” said Haden, who is also executive director of the Multidisciplinary Association for Psychedelic Studies.

Mate is an author and international speaker on repressed trauma and the emotional and physical effects of hidden stress. He said many of the illicit drug users he treated in Vancouver’s Downtown Eastside became addicted in response to unresolved traumatic experiences in childhood.

The ayahuasca concoction isn’t a take-home remedy and isn’t for people with a history of psychosis, mania, seizures or heart issues, Mate said, adding he couldn’t speculate on what set off the events leading to Woodroffe’s death, but alcohol and stimulants, such as crystal meth, are more apt to cause violence.

“I’ve participated in multiple ceremonies and I’ve seen the occasional person freak out, but rarely. I know people who’ve done or led hundreds, maybe thousands of ceremonies and never had any acts of violence.”

In December 2015, a Winnipeg man fatally stabbed a fellow tourist from England after the two drank ayahuasca together in a spiritual ceremony a few hours’ drive from where Woodroffe was killed. The men drank the hallucinogenic brew before the British tourist grabbed a butcher knife, leading the Canadian to fatally stab him in what British authorities later determined was self-defence.

Mate said that a decade ago, he led a ceremony involving ayahuasca with members of an Indigenous band in British Columbia who’d experienced multigenerational trauma.

Health Canada told him he would have to do a clinical study on the effects of the plant, but Mate said that would have cost millions of dollars.

“It’s a completely different entity,” he said of the plant. “What I wish they would do is look at it realistically and objectively based on international experience.”

Health Canada did provide an exemption to the drug several years ago for a Montreal chapter of a Brazilian religion for sacramental use of the plant.

Rhonda Nelson of Athabasca, Alta., said she went on a life-changing retreat led by Mate in 2015 to deal with anxiety and depression related to childhood trauma before attending similar ceremonies in Peru in January 2017 where she again drank ayahuasca.

“It would be akin to 10 years of psychotherapy. I was able to get in touch with that deep suffering and what the root of it was,” she said.

Nelson, 45, said she also experienced physical healing and no longer has symptoms of congenital myasthemic syndrome, a neuromuscular disorder.

“When I ingested the plant, it brought up emotion in me that I’d been familiar with me all my life but in such a way that the intensity was similar to the intensity that I experienced when it first originated in early childhood,” she said.